Synthetic aperture radar (SAR) imaging systems are widely used in aerial and space reconnaissance. Usually, an aircraft or a spacecraft is provided with a SAR imaging system which transmits radar pulses and collects radar echoes corresponding to the radar pulses reflected by an object to be imaged.
In SAR imaging systems, estimating the Doppler centroid frequency may be required for compensating for variations in the antenna beam since a Doppler frequency shift may degrade the quality of the radar image. Methods have been developed for estimating the Doppler centroid. However, these methods require the use of additional operations in the Fourier domain. Furthermore, these methods require Fourier transforms of the SAR raw data, which are processing power consuming.
Therefore there is a need for an improved method and apparatus for determining a Doppler centroid in a SAR imaging system.